1. Field of the Invention
The present invention relates to an electric nailing tool and, more particularly, to an electric nailing tool, e.g., an electric nailing gun that provides at least two impacting motions to a relatively long nail to thereby assure complete nailing engagement of two objects by the relatively long nail.
2. Description of the Related Art
FIG. 6A of the drawings illustrates a conventional nailing tool that utilizes a single solenoid 3 for moving a hammer 1 rectilinearly. When the solenoid 3 is energized by means of turning an associated switch on, a magnetic force is generated to attract the hammer 1 to move. A percussion pin 4 attached to an end of the hammer 1 impacts on a nail 5 into two stacked objects 6 and 7 to be nailed together, as shown in FIG. 6B. When the switch for controlling the solenoid 3 is turned off, no current passes through the solenoid 3 and the hammer 1 returns to its initial position under the action of a spring 2 mounted around the other end of the hammer 1. Nevertheless, the hammer 1 must be longer than the solenoid 3 to maintain rectilinear downward movement of the hammer 1. This is because the magnetic field generated by the solenoid 3 incurs a force that acts in an opposite direction and thus compromises the impact force of the hammer 1 if the hammer 1 is too short. The volume and weight of the electric nailing tool are thus increased as a result of the long hammer 1. In addition, a relatively long nail cannot be completely hammered into the objects to be nailed together, as the electric nailing tool provides only one impacting motion. Furthermore, the solenoid generates heat and thus causes high temperature after operating a long time, which would lead damage to the control circuit for the electric nailing tool and sometimes might even burn the control circuit.
U.S. Pat. No. 5,760,552 to Chen et al. issued on Jun. 2, 1998 discloses a method of controlling driving power of double-solenoid electric percussion tools. Two solenoids are used to provide the maximum driving power and speed of the hammer. Nevertheless, the electric percussion tools disclosed in this patent cannot completely hammer a relatively long nail into the objects to be nailed together, as the electric nailing tool provides only one impacting motion.
It is the primary object of the present invention to provide an electric nailing tool that provides at least two impacting motions to a relatively long nail to thereby assure complete nailing engagement of two objects by the relatively long nail.
An electric nailing tool in accordance with the present invention comprises:
a housing;
a nail magazine for supplying nails;
a spout attached to the nail magazine and comprising a passage communicated with the housing, the nail magazine feeding nails to the passage;
a solenoid set comprising at least two solenoids having a common through-hole;
a hammer mounted in the common through-hole of said at least two solenoids, the hammer including an end, a percussion member being securely attached to the end of the hammer to move therewith, the percussion member extending through the passage of the spout for driving a nail in the passage out of the spout upon percussion movement of the hammer in a direction, the hammer being biased to move in another direction opposite to the direction when none of said at least two solenoids is energized;
wherein said at least two solenoids are energized and de-energized in sequence to move the hammer back and forth along the common through-hole of said at least of solenoids, thereby providing at least two impacting motions by the percussion member to the nail in the passage.
In a first embodiment of the invention, an electric nailing tool comprises:
a housing;
a nail magazine for supplying nails;
a spout attached to the nail magazine and comprising a passage communicated with the housing, the nail magazine feeding nails to the passage;
a solenoid set comprising a first solenoid and a second solenoid that have a common through-hole;
a hammer mounted in the common through-hole, the hammer including an end, a percussion member being securely attached to the end of the hammer to move therewith, the percussion member extending through the passage of the spout for driving a nail in the passage out of the spout upon percussion movement of the hammer in a first direction, the hammer being biased by an elastic element to move in a second direction opposite to the first direction when none of the solenoids is energized;
wherein the end of the first solenoid rests at an initial position in the first solenoid when non of the solenoids is energized;
wherein when the first solenoid is energized, the hammer is moved in the first direction, and the first solenoid is de-energized when the end of the hammer reaches a first position in the second solenoid and the hammer moves in the second direction under action of the elastic element;
wherein the second solenoid is energized when the end of the hammer reaches a second position that is between the initial position and the first position, thereby moving the hammer in the first direction again until the end of the hammer reaches a position farther than the first position.
In a second embodiment of the invention, an electric nailing tool comprises:
a housing;
a nail magazine for supplying nails;
a spout attached to the nail magazine and comprising a passage communicated with the housing, the magazine feeding nails to the passage;
a solenoid set comprising a first solenoid, a second solenoid, and a third solenoid that have a common through-hole;
a hammer mounted in the common through-hole, the hammer including an end, a percussion member being securely attached to the end of the hammer to move therewith, the percussion member extending through the passage of the spout for driving a nail in the passage out of the spout upon percussion movement of the hammer in a first direction, the hammer being biased by an elastic element to move in a second direction opposite to the first direction when none of the three solenoids is energized;
wherein the end of the first solenoid rests at an initial position in the first solenoid when non of the solenoids is energized;
wherein when the first solenoid is energized, the hammer is moved in the first direction, and the first solenoid is de-energized when the end of the hammer reaches a first position outside the first solenoid and the hammer moves in the second direction under action of the elastic element;
wherein the second solenoid is energized when the end of the hammer reaches a second position that is between the initial position and the first position, thereby moving the hammer in the first direction again, the second solenoid is de-energized when the end of the hammer reaches a third position farther than the first position and the hammer moves in the second direction under action of the elastic element;
wherein the third solenoid is energized when the end of the hammer reaches a fourth position between the second position and the third position, thereby moving the hammer in the first direction again until the end of the hammer reaches a position farther than the first position.
The spout further comprises an actuating rod. The electric nailing tool further comprises a trigger and a safety switch that is mounted in the housing. The trigger is inoperative when the actuating rod is not pressed against an object to be nailed. Trigger is operative when the actuating rod is pressed against the object to be nailed and thus impinges the safety switch.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.